Google has updated the localized versions of your leaf assistance document to alter all the hreflang examples from lowercase codes to uppercase codes. It doesn't matter since the hreflang value is case-insensitive; Google accepts lowercase and uppercase codes.
Google additionally posted a new row that explains why the alter to uppercase, Google wrote:
The hreflang value is case-insensitive; Google accepts lowercase and uppercase codes, but formatting area codes in uppercase (for example, en-GB) follows ISO 3166-1 Alpha 2 convention.
Here is a screenshot of the content added to this assistance document:
Here is what the old page had, as an example:
Here is the new type alongside uppercase codes:
You should likely be accordant whenever you do the uppercase or lowercase codes but hey, Google did alter all their records to uppercase.
Forum conversation at X.
